POSTERIOR SHOULDER TIGHTNESS AND SUBACROMIAL IMPINGEMENT CHARACTERISTICS IN BASEBALL PITCHERS: A BLINDED, MATCHED CONTROL STUDY

Abstract

Background: Baseball pitchers frequently develop varying levels of posterior shoulder tightness (PST) and often present with characteristics associated with subacromial impingement. Purpose: To determine if a group of baseball pitchers with excessive PST (bilateral internal rotation ROM difference >18° and bilateral total arc of motion difference >5°) have differences in subacromial joint space, forward scapular posture, or glenohumeral elevation range of motion (ROM) when compared to a control group. Study Design: Descriptive, cross-sectional study. Methods: Thirty-five asymptomatic professional baseball pitchers with excessive PST were matched with 35 pitchers with acceptable levels of PST. The investigators measured subacromial space using diagnostic ultrasound, glenohumeral elevation ROM using a digital goniometer, and scapular posture using a double square, and were blinded to the group of each participant. Separate t-tests were used to determine signifi-cant differences between groups (p<0.05). Results: The excessive PST group presented with significantly less subacromial space (p=.0007) and gle-nohumeral elevation ROM (p=.03) compared to the acceptable level PST group. The excessive PST group also had significantly more forward scapular posture than the control group (p=.03). Conclusion: The baseball pitchers with excessive PST had less subacromial space and glenohumeral elevation ROM, as well as more forward scapular posture in their throwing arms compared to pitchers with acceptable levels of PST.